Curing & Smoking of Meat

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Background & History

• Many methods of preserving meat have been used throughout history.

• Sumerians first to salt meat over 5,000 years ago.• Ancient Hebrews used salt from Dead Sea to preserve meat

4000 years ago• Possible that smoking of meats was “accidentally discovered”

by Native Americans.– Hung meat from tops of teepees

• In 1970’s 80’s ingredients used in curing and smoking were heavily researched– Possible health implications (cancer, etc.)

What is Curing?

• Curing is addition of salt, sugar, and nitrite or nitrate to meats for purpose of preservation, flavor enhancement, or color development.

• Today curing is performed more for flavordevelopment than for preservation

Other functions of curing

– Shelf life extension– Development of unique properties– Resistance to rapid deterioration– Controlling microbial growth.

Curing Ingredients• Salt (NaCl)

– Contributes flavor– Preservative effect– Controls microbial growth (doesn’t kill bacteria)– Osmosis (enhances transport of nitrate, nitrite, and sugar)– Can be in granular or rock forms.– Only difference is quantity of NaCl in the salt.

Curing Ingredients

• Sugar (C12H22O11)– Contributes flavor– Counteracts salt– Provides source of energy for nitrate converting bacteria– Lowers the acidity of the cure– Can be added in the form of:

• Sucrose (table sugar/brown sugar)• Dextrose (refined corn sugar)• Corn syrup solids

– RRM uses powdered sugar• Finer particle size easier to dissolve in water

– Commercial cures use corn syrup solids• Cheaper• May require more to get same flavor

Curing Ingredients

• Nitrite (NaNO2) or Nitrate (NaNO3)– Contributes flavor– Prevents warmed-over flavor (WOF) in reheated products – Retards development of rancidity during storage– Prevents growth of C. boltulinum in canned products– Bacteriostatic – Contributes cured-pink color to the product.

Nitrites & Nitrates• Usually come in the form of potassium or sodium nitrites or nitrates.• FSIS allows use of nitrate (NaNO3 or KNO3) ONLY in dry cured meats or dry

sausage.• FSIS permits use of Nitrites (NaNO2 or KNO2) in bacon

– Ingoing nitrite level cannot exceed 120 ppm • Must be accompanied by 550ppm sodium ascorbate or sodium

erythorbate– Residual nitrite must not exceed 40 ppm

• Nitrites and Nitrates can be carcinogenic.– MIT Study: 40 pounds of bacon/day for 40 years

• Currently seeing increase of “No Nitrite” or “Uncured” products

Curing Reaction• Basic Cure Reaction (1st Step)

Deoxymyoglobin + Nitric Oxide = Nitric Oxide Myoglobin (purplish red) (red)

• Nitric Oxide is generated during curing sequence

NaNO3NaNO2 HONO NO

Nitrate Nitrite Nitrous Acid Nitric Oxide• Nitric Oxide myoglobin in unstable

– Color must be “fixed” by heating to 140 degrees.

Curing Reaction• Fixation Reaction

Nitric oxide myoglobin +Heat = Nitrosylhemochromagen (red) (cured pink)

– Nitrosylhemochromagen is responsible for stable cured-pink color.– Very Heat Stable- pink color doesn’t change with further cooking– Only occurs with the addition of heat

• Overall ReactionMyoglobin + NO Nitric Oxide Myoglobin Nitrosylhemochromagen

(purplish red) (red) HEAT (cured pink)

Curing Adjuncts• Proper color development is a function of time• Ascorbic Acid, Sodium Ascorbate and Sodium Erythorbate speed

color development• Ascorbates reduce Metmyoglobin to Myoglobin– Metmyoglobin is unable to combine with NO, while Myoglobin

can• Ascorbates speed reduction of HONO to NO– Greater quantities of NO available for production

• Treatment of cured cuts with 5-10% Ascorbic Acid– Effective in reducing fading of cured color in displays

Alkaline Phosphates

• Usually Sodium Tripolyphosphate• Added to decrease shrink during curing &

smoking• Cannot exceed 0.5%• Increase water holding capacity (WHC) of

muscle proteins

Water

• Water is “curing ingredient” when doing Cover Pickle Curing (Brine) or Injection Curing

• Disperses cure throughout meat• Use of water reduces cost of products – Products with more water are cheaper

• Water remaining in retail product is “Added Water”

Protein Fat Free Method• Method for calculating added water.• Set Standards for measuring minimum meat-protein content in cured pork

on fat-free basis• PFF Value = (Percent of meat protein)/(100-percent of fat) X 100

• Use of Alkaline Phosphates– Tremendous quantities of cure added to cuts and still remain normal

• FSIS uses PFF to regulate amount of moisture in final product– Ham (Minimum 20.5% PFF)– Ham with Natural Juices (Minimum 18.5% PFF)– Ham, Water Added (Minimum 17% PFF)– Ham and Water Product (Less Than 17% PFF)

Application of Curing Ingredients• Dry Curing– Use of salt or salt plus nitrite or nitrate– Dry Sugar Curing• Uses Sugar to overcome harshness of salt flavor

– Both methods involve rubbing cure mixture over surface– Penetration of NaCl occurs through osmosis– Bone Sour (souring around bones) occurs in hams• Lack of rapid-enough salt penetration to interior

– High levels of shrinking

Application of Curing Ingredients

• Curing With Liquid– Can either be Cover Pickle (placing meat in brine) or Sweet

Pickle (sugar added to brine)– Penetration of cure occurs via osmosis– More uniform distribution of cure– Can Result in Bone Sour– Can result in yeast growth

Injection Curing– Three forms of injection curing

1. Stitch or spray pumping– Cure directly injected into meat with

needles2. Artery Pumping

– Accomplishes best possible distribution of cure

– Cure dispersed via capillaries

3. Multi-needle Machine Injection–Most commercial facilities use– Rapid penetration of cure into

meat (reduce spoilage)– Less spoilage and shrinkage– Not conducive to development

of typical flavor, aroma, and texture

Massaging & Tumbling• Massaging and Tumbling occur after Pumping

– Extract muscle proteins to bind the muscles together

– Allow for increased pickup & retention of moisture

• Function of Massaging and Tumbling– Disruption of Tissue Structure– Hastening of Cure-Ingredient Distribution– Solubilization of muscle proteins

• Massaging– Relies on frictional energy– Minimizes the tearing of muscles– Minimizes particle size reduction

• Tumbling– Relies on impact energy– Extracts myofibrillar proteins

Smoking of Meat Products• Materials used for smoke come from hardwood sawdust or

chips– Softwood products result in sooty deposit.

• Over 200 components comprise smoke– At least 80 have been identified– Almost all exhibit bacteriostatic or bacteriocidal properties

• Smoke consists of two parts– Dispersed phase- consists of parts that are 2-3

micrometers in size• Tars, soot, charcoal, and resins

– Gaseous phase- Not visible• Phenols, acids, and carbonyl compounds

Smoking of Meat Products

• Benefits of Smoking– Flavor and Odor Enhancement– Color Development on Outside of Product– Preservation of the product

• Liquid smoke- widely used in industry– Wood combustion products dissolved in water– Cheaper and quicker than the smokehouse process